1. Field of the Invention
The present invention relates to printing apparatuses and printing methods.
2. Description of the Related Art
A printing apparatus for printing on a sheet and outputting the printed sheet to a stacking unit, such as a paper output tray, is conventionally known. The following two modes are known as output modes (output methods) for outputting a printed sheet to a stacking unit. A first mode is a face-up (FU) output mode in which a sheet is ejected with its printed surface facing upward. A second mode is a face-down (FD) output mode in which a sheet is ejected with its printed surface facing downward. Since a printing apparatus typically includes only one print processing unit for printing on a sheet, the printing apparatus allows switching between the face-up output mode and the face-down output mode by turning the sheet upside down.
There is a known printing apparatus which allows switching between the above-described face-up output mode and face-down output mode according to an instruction from an operator (see, e.g., Japanese Patent Laid-Open No. 2005-121716). This known technique enables the operator of the printing apparatus to select either the face-up output mode or the face-down output mode as desired. However, it is possible that this technique may cause some problems.
When a plurality of sheet bundles corresponding to a plurality of print jobs are to be stacked on a stacking unit of the printing apparatus, the above-described technique allows the operator to instruct the printing apparatus to, for example, eject a sheet bundle corresponding to a first print job in the face-down output mode and to eject a sheet bundle corresponding to a second print job in the face-up output mode. In this case, the sheet bundle ejected in the face-down output mode and the sheet bundle ejected in the face-up output mode are placed on the stacking unit of the printing apparatus in a mixed manner.
A problem may arise if a plurality of sheet bundles corresponding to a plurality of print jobs are printed by the printing apparatus and, for example, collectively processed by a sheet processing apparatus outside the printing apparatus. That is, a problem may arise if sheet processing is performed collectively on the mixture of sheet bundles ejected in the face-down output mode and face-up output mode. For example, if a stack of sheets is to be cut off at one end by the sheet processing apparatus, a problem will occur unless sheet bundles ejected in the face-down output mode and sheet bundles ejected in the face-up output mode are sorted appropriately. Specifically, some sheet bundles may be cut off at the right ends of printed surfaces, while other sheet bundles may be cut off at the left ends of printed surfaces.